Aquatic Toxicology and Stress Responses in Fish Systems

Aquatic toxicology in fish encompasses the study of how chemical, physical and biological stressors—ranging from industrial pollutants and agrochemicals to natural plant piscicides and parasitic infestations—interact with fish physiology at molecular, cellular and whole‐organism levels. Exposure to toxicants may disrupt endocrine function, impair respiratory surfaces, induce oxidative stress and provoke immunological or behavioural changes. Fish respond through induction of antioxidant enzymes, activation of heat‐shock proteins, modification of metabolic pathways and alterations in gill and liver histology. These responses underpin the use of biochemical and cellular biomarkers—such as lipid peroxidation products, enzyme activities and histopathological lesions—in environmental monitoring and risk assessment. Understanding stress response mechanisms supports the development of mitigation strategies for aquaculture and the conservation of wild populations, with relevance for food security, ecosystem health and regulatory policy worldwide.

Research from Nature Portfolio

Recent studies have explored botanical interventions for managing parasitic and helminthic burdens in fish. One investigation assessed ethanolic and aqueous extracts of five tropical plants—Aframomum melegueta, Moringa oleifera, Azadirachta indica, Zingiber officinale and Allium sativum—against multiple helminth parasites in Clarias gariepinus. Results demonstrated over 70% efficacy at sub‐lethal concentrations comparable to praziquantel, with a wide safety margin for the host and negligible behavioural disruption. Another study evaluated the methanol extract of Nephrolepis biserrata against the marine leech Zeylanicobdella arugamensis infesting hybrid groupers. Dose‐dependent mortality was achieved within minutes, and comprehensive metabolite profiling revealed terpenoids, flavonoids and phenolics responsible for antiparasitic activity, highlighting a promising biocontrol agent for sustainable aquaculture.

Aquatic Toxicology and Stress Responses in Fish Systems publication trend

The graph below shows the total number of articles in aquatic toxicology and stress responses in fish systems across all publications each year (not limited to Nature Index journals).

Technical terms

LC50: Concentration of a substance that causes death in 50% of a test population over a specified time.
Oxidative stress: Cellular damage resulting from an imbalance between reactive oxygen species and antioxidant defences.
Histopathology: Microscopic examination of tissues to identify structural alterations induced by toxicants.
Biomarker: A measurable indicator of exposure or effect in an organism.
Anthelmintic: Substance that expels or kills helminth parasites.
Piscicide: Chemical agent used to eliminate fish or aquatic organisms.
Metabolite profiling: Characterisation of small molecules produced by an organism in response to treatments.
Hyperplasia: Increase in the number of cells in a tissue, often as a response to injury or stress.
Reactive oxygen species (ROS): Highly reactive molecules derived from oxygen that can damage cellular components.

References

1. Phytochemical profiling and anthelmintic potential of extracts of selected tropical plants on parasites of fishes in Epe Lagoon. Scientific Reports (2023).
2. Antiparasitic potential of Nephrolepis biserrata methanol extract against the parasitic leech Zeylanicobdella arugamensis (Hirudinea) and LC-QTOF analysis. Scientific Reports (2020).
3. Ichthyotoxicity of ethanolic extract of Justicia extensa on behavioral and histopathological changes in Clarias gariepinus (Burchell, 1822). Environmental Chemistry and Ecotoxicology (2022).
4. Antiparasitic Potential of Methanol Extract of Brown Alga Sargassum polycystum (Phaeophyceae) and Its LC-MS/MS Metabolite Profiling. Diversity (2022).
5. Evaluation of oxidative stress markers in the heart and liver of rainbow trout (Oncorhynchus mykiss walbaum) exposed to the formalin. Fish Physiology and Biochemistry (2016).